In modern and future communication systems, location services and location-based services (LCS) are gaining more attention and importance. In order to enable provision of location services and location-based services for terminals in modern and future communication systems, an accurate positioning of the terminals is vital. An accurate positioning is for example particularly valuable in emergency use cases, under indoor conditions, urban canyons, tunnels, parking halls, subways, vehicles, and the like.
In the framework of 3GPP standardization, LTE control plane signaling support for LCS is introduced from 3GPP Release 9 onwards. Therein, assisted satellite positioning is specified as a primary positioning/localization technique, while both a cell ID based positioning and OTDOA-based positioning are specified as fallback positioning/localization techniques for the event that the terminal lacks satellite positioning capability or the assisted satellite positioning fails e.g. due to non-availability of a required number of positioning satellite signals.
The assisted satellite positioning is essentially based on at least four positioning satellite signals of GPS or any other satellite-based positioning system, while the network can provide assistance data for a reliable fix of the position.
The cell ID based positioning and enhancements thereof are essentially based on the fact that the responsible server (e.g. E-SMLC) knows the geographical locations of the cells, that the timing advance can be used to find a terminal's distance from each base station antenna in the vicinity, and that neighbor cell measurements and the like can be used to increase the accuracy of the positioned. That is to say, the consideration of neighbor cells enhances accuracy of positioning.
The OTDOA-based positioning is essentially based on the measurement of an observed time difference of arrival (OTDOA) on the basis of a positioning-related signal. In this regard, a terminal's position can be multi-laterated (mostly tri-laterated) with the knowledge of multiple (mostly three or more) base stations' transmit timings and their geographical locations and received time differences of at least two other cells relative to the serving cell of the terminal. In this regard, the terminal must detect positioning-related signals from multiple (mostly at least three) base stations in the vicinity.
Generally, when an increased accuracy of positioning results is desired in a specific communication system, the accuracy of positioning of at least one of the positioning/localization techniques specified for that specific communication system is to be improved. In view of the above, in the context of a 3GPP-based LTE communication system, the accuracy of positioning of at least one of assisted satellite positioning, the cell ID based positioning and the OTDOA-based positioning is to be improved.
The accuracy of positioning of the assisted satellite positioning and the cell ID based positioning may not be easily improved without requiring fundamental changes to the functional and/or structural configuration of the underlying satellite-based positioning system and communication system, respectively. Therefore, when an increased accuracy of positioning results is desired in a 3GPP-based LTE communication system, the accuracy of positioning of the OTDOA-based positioning is preferably to be improved.
Generally speaking, the positioning accuracy of a timing-based positioning technique (e.g. the OTDOA-based positioning technique) may typically be improved, while the positioning accuracy of infrastructure-based positioning technique is typically difficult to improve without effecting fundamental modifications to the underlying infrastructure.
Accordingly, in order to increase accuracy of positioning results in a specific communication system, it is desirable to improve the positioning accuracy of a timing-based positioning technique therein, which may typically be achieved when improving underlying timing information and/or timing measurements.
Thus, there is a desire to improve timing-based positioning accuracy.